The whole idea of splitting enmity into multiple fronts would most definitely change how players get hate. Having Melee/Magic/Other Would allow melee to cap out hate rather fast in it's category but not effect magic, Where as magic nuking would only affect nuking. Others would be outside directly affecting the target IE buffs and cures on someone who had hate (including yourself) would raise this. The enemy would base their hate target on the average or of the three or average divisible by two for all these combined right? If so this would allow PLD and a few others to tank better because they could boost enmity on multiple fronts allowing for a much larger variances of hate while making it harder to cap total average hate. Others would be limited if they only utilize just using one or two of the hate utilities.
Very very very nice that's fostering better play.
Now that I think about it I think there could be another way to fix enmity by altering it so as hate increases the ability gain it decreases exponentially so it's nearly impossible to ever cap hate unless you use tools or abilities that deliberately bypass this.
If SE wants to fix the AOE issues PLD must have a better way to create an AURA of protection that actually last, with a short recast. Something like boost every 15 seconds that stacks on others. This means the tank would need to work protect everyone else. If PLD is so powerful now then this aura effect could even transfer a portion of the damage to the tank. It would definitely give players a reason to put a real tank back into the party.